Github user tejasapatil commented on a diff in the pull request:
https://github.com/apache/spark/pull/16985#discussion_r102245647
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/joins/SortMergeJoinExec.scala
---
@@ -33,8 +33,8 @@ import org.apache.spark.util.collection.BitSet
* Performs a sort merge join of two child relations.
*/
case class SortMergeJoinExec(
- leftKeys: Seq[Expression],
- rightKeys: Seq[Expression],
+ var leftKeys: Seq[Expression],
--- End diff --
@hvanhovell : I had tried that but for some class of queries that didn't
work. When I try to get the `outputPartitioning` for a SMB node, in [case of
inner-join it
is](https://github.com/apache/spark/blob/02f203107b8eda1f1576e36c4f12b0e3bc5e910e/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/SortMergeJoinExec.scala#L68)
`PartioniningCollection`. Now one of its children can have a `ReusedExchange`
which is yet to be resolved but if the other child is resolved, then [this
check](https://github.com/apache/spark/blob/39e2bad6a866d27c3ca594d15e574a1da3ee84cc/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/physical/partitioning.scala#L325)
fails.
Example query:
```
SELECT a.i, b.i, c.i
FROM mytable a, mytable b, mytable c
where a.i = b.i and a.i = c.i
```
Example query plan:
```
:- *SortMergeJoin [i#8], [i#9], Inner
: :- *Sort [i#8 ASC NULLS FIRST], false, 0
: : +- Exchange hashpartitioning(i#8, 200)
: : +- *Project [i#8]
: : +- *Filter isnotnull(i#8)
: : +- *FileScan orc default.one_column[i#8] Batched: false,
Format: ORC, Location:
InMemoryFileIndex[file:/Users/tejasp/Desktop/dev/tp-spark/spark-warehouse/one_column],
PartitionFilters: [], PushedFilters: [IsNotNull(i)], ReadSchema: struct<i:int>
: +- *Sort [i#9 ASC NULLS FIRST], false, 0
: +- ReusedExchange [i#9], Exchange hashpartitioning(i#8, 200)
```
Just to be on the same page, sharing what I had tried (will update the PR
with the change anyways. I know that there would be some unit tests which would
fail):
```
case class SortMergeJoinExec(
leftKeys: Seq[Expression],
rightKeys: Seq[Expression],
....) {
lazy val (reorderedLeftKeys, reorderedRightKeys) = {
def reorder(
expectedOrderOfKeys: Seq[Expression],
currentOrderOfKeys: Seq[Expression]): (Seq[Expression],
Seq[Expression]) = {
val leftKeysBuffer = ArrayBuffer[Expression]()
val rightKeysBuffer = ArrayBuffer[Expression]()
expectedOrderOfKeys.foreach(expression => {
val index = currentOrderOfKeys.indexWhere(e =>
e.semanticEquals(expression))
leftKeysBuffer.append(leftKeys(index))
rightKeysBuffer.append(rightKeys(index))
})
(leftKeysBuffer, rightKeysBuffer)
}
left.outputPartitioning match {
case HashPartitioning(leftExpressions, _)
if leftExpressions.length == leftKeys.length &&
leftKeys.forall(x => leftExpressions.exists(_.semanticEquals(x)))
=>
reorder(leftExpressions, leftKeys)
case _ => right.outputPartitioning match {
case HashPartitioning(rightExpressions, _)
if rightExpressions.length == rightKeys.length &&
rightKeys.forall(x =>
rightExpressions.exists(_.semanticEquals(x))) =>
reorder(rightExpressions, rightKeys)
case _ => (leftKeys, rightKeys)
}
}
}
```
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